Definition of "man-hour"

[...] every man has tools and amenities always within one minute's walk; thus non-productive man-hours are kept to a minimum.

1960 December, “New G.E. Line diesel loco maintenance depot at Stratford”, in Trains Illustrated, page 766

Since 1950 our agricultural output per man-hour has actually doubled!

1962 January 11, John F. Kennedy, Second State of the Union Address